Impacts of deficit irrigation and humic acid application on growth, yield and fruit quality of Valencia orange trees

doi:10.21608/ejoh.2015.1309

Impacts of deficit irrigation and humic acid application on growth, yield and fruit quality of Valencia orange trees

Document Type : Original Article

10.21608/ejoh.2015.1309

Abstract

THE PRESENT investigation was conducted during 2010 and 2011 ….. growing seasons in order to study the effects of deficit irrigation (DI) and humic acid applications on the growth, yield and fruit quality of five-year-old Valencia orange trees (Citrus sinensis L.) grown under intensive cultivation conditions (1.5m x 4.5m) in raised beds of sandy soil in Mariot region located 45 Km at Alexandria Desert Road. Three irrigation regimes were imposed: (1) Standard practice irrigation (control): Re-irrigation immediately when soil moisture tension reached 15 kPa, (2) Moderate deficit irrigation (MDI): Re-irrigation 2 days after reaching a soil moisture tension of 15 kPa, and (3) Severe deficit irrigation (SDI): Re-irrigation 4 days after reaching a soil moisture tension of 15 kPa. Humic acid was applied as a soil conditioner (75 ml /tree/season) to test whether it can alleviate the negative impacts of irrigation water deficit. Irrigation deficit treatments significantly decreased shoot length, leaf area, fruit set, fruit weight and yield, but increased peel thickness, total soluble solids, acidity and maturity index. Humic acid application to the standard practice irrigation enhanced growth parameters, fruit set, yield and fruit weight, but did not affect peel thickness and total soluble solids in the first season, acidity, vitamin C and maturity index. There were no significant effects for humic acid on growth and fruit quality parameters in deficit irrigation treatments except for fruit weight in both seasons and yield in the first season.

Keywords